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                    updateSuspenseComponent
            
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                    updatePortalComponent
            
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                    updateForwardRef
            
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                    updateFragment
            
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                    updateProfiler
            
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                    updateContextProvider
            
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                    lazy 组件
            
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                                <h1 id="lazy-component">lazy component</h1><p>&#x901A;&#x8FC7;<code>React.lazy</code>&#x6211;&#x4EEC;&#x975E;&#x5E38;&#x65B9;&#x4FBF;&#x5730;&#x5B9E;&#x73B0;&#x5F02;&#x6B65;&#x52A0;&#x8F7D;&#x6A21;&#x5757;&#x7684;&#x529F;&#x80FD;&#xFF0C;&#x901A;&#x8FC7;&#x8FD9;&#x4E2A; API &#x521B;&#x5EFA;&#x7684;&#x5BF9;&#x8C61;&#x5982;&#x4E0B;&#xFF1A;</p><pre><code class="lang-js">{
  $$<span class="hljs-keyword">typeof</span>: REACT_LAZY_TYPE,
  _ctor: ctor,
  <span class="hljs-comment">// React uses these fields to store the result.</span>
  _status: <span class="hljs-number">-1</span>,
  _result: <span class="hljs-literal">null</span>,
}</code></pre>
<p>&#x5176;&#x4E2D;<code>_status</code>&#x548C;<code>_result</code>&#x4E24;&#x4E2A;&#x503C;&#x662F;&#x975E;&#x5E38;&#x91CD;&#x8981;&#x7684;&#xFF0C;&#x7528;&#x6765;&#x6807;&#x8BB0;&#x52A0;&#x8F7D;&#x5B8C;&#x6210;&#x7684;&#x6A21;&#x5757;&#x7684;&#x5185;&#x5BB9;&#xFF0C;&#x800C;<code>_ctor</code>&#x5219;&#x8BB0;&#x8F7D;&#x4E86;&#x6211;&#x4EEC;&#x4F20;&#x5165;&#x7684;&#x751F;&#x4EA7;<code>thenable</code>&#x5BF9;&#x8C61;&#x7684;&#x65B9;&#x6CD5;&#x3002;</p><p>&#x5728;&#x66F4;&#x65B0;&#x8FC7;&#x7A0B;&#x4E2D;&#xFF0C;&#x6211;&#x4EEC;&#x9047;&#x5230;<code>lazy</code>&#x7EC4;&#x4EF6;&#x4F1A;&#x600E;&#x4E48;&#x6837;&#x5462;&#xFF1F;</p><pre><code class="lang-js"><span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">mountLazyComponent</span>(<span class="hljs-params">
  _current,
  workInProgress,
  elementType,
  updateExpirationTime,
  renderExpirationTime,
</span>) </span>{
  <span class="hljs-keyword">if</span> (_current !== <span class="hljs-literal">null</span>) {
    _current.alternate = <span class="hljs-literal">null</span>
    workInProgress.alternate = <span class="hljs-literal">null</span>
    workInProgress.effectTag |= Placement
  }

  <span class="hljs-keyword">const</span> props = workInProgress.pendingProps
  cancelWorkTimer(workInProgress)
  <span class="hljs-keyword">let</span> Component = readLazyComponentType(elementType)
  workInProgress.type = Component
  <span class="hljs-keyword">const</span> resolvedTag = (workInProgress.tag = resolveLazyComponentTag(Component))
  startWorkTimer(workInProgress)
  <span class="hljs-keyword">const</span> resolvedProps = resolveDefaultProps(Component, props)
  <span class="hljs-keyword">let</span> child
  <span class="hljs-keyword">switch</span> (resolvedTag) {
    <span class="hljs-comment">// &#x6839;&#x636E;&#x8FD4;&#x56DE;&#x7684;&#x7EC4;&#x4EF6;&#x7C7B;&#x578B;&#x6267;&#x884C;&#x66F4;&#x65B0;</span>
    <span class="hljs-keyword">default</span>: {
      <span class="hljs-comment">// warning</span>
    }
  }
  <span class="hljs-keyword">return</span> child
}</code></pre>
<p>&#x9996;&#x5148;&#x6211;&#x4EEC;&#x770B;&#x5230;&#x5982;&#x679C;<code>_current</code>&#x5B58;&#x5728;&#x503C;&#x4F1A;&#x5F3A;&#x884C;&#x5220;&#x9664;<code>current</code>&#x7684;&#x5F15;&#x7528;&#xFF0C;&#x4E3A;&#x4EC0;&#x4E48;&#x8981;&#x8FD9;&#x4E48;&#x505A;&#x5462;&#xFF1F;&#x56E0;&#x4E3A;<code>lazy</code>&#x7EC4;&#x4EF6;&#x53EA;&#x6709;&#x5728;&#x7B2C;&#x4E00;&#x6B21;&#x6E32;&#x67D3;&#x7684;&#x65F6;&#x5019;&#x624D;&#x4F1A;&#x8C03;&#x7528;&#x8BE5;&#x65B9;&#x6CD5;&#xFF0C;&#x7B49;&#x5230;&#x7EC4;&#x4EF6;&#x5DF2;&#x7ECF;&#x52A0;&#x8F7D;&#x5B8C;&#x6210;&#x4E86;&#xFF0C;&#x5C31;&#x4F1A;&#x8D70;&#x76F4;&#x63A5;&#x66F4;&#x65B0;&#x7EC4;&#x4EF6;&#x7684;&#x6D41;&#x7A0B;&#xFF0C;&#x5177;&#x4F53;&#x8BC1;&#x636E;&#x5C31;&#x662F;&#x4E0B;&#x9762;&#x8FD9;&#x53E5;&#x4EE3;&#x7801;&#xFF1A;</p><pre><code class="lang-js"><span class="hljs-keyword">const</span> resolvedTag = (workInProgress.tag = resolveLazyComponentTag(Component))</code></pre>
<p><code>resolveLazyComponentTag</code>&#x662F;<code>ReactFiber</code>&#x63D0;&#x4F9B;&#x7684;&#x6839;&#x636E;&#x7279;&#x6027;&#x5224;&#x65AD;&#x7EC4;&#x4EF6;&#x7C7B;&#x578B;&#x7684;&#x65B9;&#x6CD5;&#xFF0C;&#x53EF;&#x4EE5;&#x5224;&#x65AD;&#x662F;<code>ClassComponent</code>&#x8FD8;&#x662F;<code>FunctionalComponent</code>&#x8FD8;&#x662F;&#x4E00;&#x4E9B;&#x5185;&#x7F6E;&#x7C7B;&#x578B;&#x3002;&#x5728;&#x7EC4;&#x4EF6;&#x52A0;&#x8F7D;&#x5B8C;&#x6210;&#x4E4B;&#x540E;&#xFF0C;&#x5C31;&#x76F4;&#x63A5;&#x8BBE;&#x7F6E;<code>tag</code>&#x4E3A;&#x65B0;&#x7684;&#x7C7B;&#x578B;&#x4E86;&#xFF0C;&#x5E76;&#x4E14;&#x8BBE;&#x7F6E;&#x4E86;<code>type</code>&#x4E3A;&#x8FD4;&#x56DE;&#x7684;<code>Component</code>&#xFF0C;&#x5C31;&#x53D8;&#x6210;&#x4E86;&#x5F02;&#x6B65;&#x52A0;&#x8F7D;&#x8FC7;&#x6765;&#x7684;&#x7EC4;&#x4EF6;&#x4E86;&#x3002;</p><p>&#x90A3;&#x4E48;&#x5982;&#x679C;&#x8FD8;&#x6CA1;&#x52A0;&#x8F7D;&#x5B8C;&#x6210;&#x5462;&#xFF1F;&#x6211;&#x4EEC;&#x6765;&#x770B;<code>readLazyComponentType</code></p><pre><code class="lang-js"><span class="hljs-keyword">export</span> <span class="hljs-keyword">const</span> Pending = <span class="hljs-number">0</span>
<span class="hljs-keyword">export</span> <span class="hljs-keyword">const</span> Resolved = <span class="hljs-number">1</span>
<span class="hljs-keyword">export</span> <span class="hljs-keyword">const</span> Rejected = <span class="hljs-number">2</span>

<span class="hljs-keyword">export</span> <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">readLazyComponentType</span>&lt;<span class="hljs-title">T</span>&gt;(<span class="hljs-params">lazyComponent: LazyComponent&lt;T&gt;</span>): <span class="hljs-title">T</span> </span>{
  <span class="hljs-keyword">const</span> status = lazyComponent._status
  <span class="hljs-keyword">const</span> result = lazyComponent._result
  <span class="hljs-keyword">switch</span> (status) {
    <span class="hljs-keyword">case</span> Resolved: {
      <span class="hljs-keyword">const</span> Component: T = result
      <span class="hljs-keyword">return</span> Component
    }
    <span class="hljs-keyword">case</span> Rejected: {
      <span class="hljs-keyword">const</span> error: mixed = result
      <span class="hljs-keyword">throw</span> error
    }
    <span class="hljs-keyword">case</span> Pending: {
      <span class="hljs-keyword">const</span> thenable: Thenable&lt;T, mixed&gt; = result
      <span class="hljs-keyword">throw</span> thenable
    }
    <span class="hljs-keyword">default</span>: {
      lazyComponent._status = Pending
      <span class="hljs-keyword">const</span> ctor = lazyComponent._ctor
      <span class="hljs-keyword">const</span> thenable = ctor()
      thenable.then(
        moduleObject =&gt; {
          <span class="hljs-keyword">if</span> (lazyComponent._status === Pending) {
            <span class="hljs-keyword">const</span> defaultExport = moduleObject.default
            lazyComponent._status = Resolved
            lazyComponent._result = defaultExport
          }
        },
        error =&gt; {
          <span class="hljs-keyword">if</span> (lazyComponent._status === Pending) {
            lazyComponent._status = Rejected
            lazyComponent._result = error
          }
        },
      )
      lazyComponent._result = thenable
      <span class="hljs-keyword">throw</span> thenable
    }
  }
}</code></pre>
<p>&#x8FD9;&#x91CC;&#x5C31;&#x7528;&#x5230;&#x4E86;<code>_status</code>&#x548C;<code>_result</code>&#xFF0C;&#x4E00;&#x5F00;&#x59CB;<code>_status</code>&#x662F;<code>-1</code>&#xFF0C;&#x6240;&#x4EE5;&#x4E0D;&#x7B26;&#x5408;&#x524D;&#x4E09;&#x4E2A;<code>case</code>&#xFF0C;&#x7136;&#x540E;&#x5C31;&#x8FDB;&#x5165;<code>default</code>&#xFF0C;&#x8FD9;&#x91CC;&#x9762;&#x8C03;&#x7528;&#x4E86;<code>_ctor</code>&#x521B;&#x5EFA;&#x4E86;<code>thenable</code>&#x5BF9;&#x8C61;&#xFF0C;&#x8C03;&#x7528;<code>then</code>&#x65B9;&#x6CD5;&#xFF0C;<code>resolve</code>&#x548C;<code>reject</code>&#x4E4B;&#x540E;&#x4F1A;&#x5206;&#x522B;&#x8BBE;&#x7F6E;<code>_status</code>&#x548C;<code>_result</code>&#xFF0C;&#x9ED8;&#x8BA4;<code>_status</code>&#x53D8;&#x6210;<code>pendding</code>&#xFF0C;&#x6240;&#x4EE5;&#x4E0B;&#x4E00;&#x6B21;&#x8FDB;&#x6765;&#x4F1A;<code>throw thenable</code>&#xFF0C;&#x8FD9;&#x5C31;&#x8FDB;&#x5165;&#x4E86;<code>Suspense</code>&#x7684;&#x9636;&#x6BB5;&#x4E86;&#x3002;</p>
                                
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